Minor shift quality (S/Q) issues are sometimes found in new production vehicles due to part to part variation in engine and automatic transmission manufacturing. It is not uncommon for shift quality issues to be one of the most common complaints reported by customers of vehicle programs. A significant portion of these complaints regarding shift quality occur due to an event that only occurs once or twice early in the ownership's experience (e.g., feels like rough transmission, hesitation happened once) and which cannot typically be duplicated if the vehicle is brought into the dealership for analysis and correction of the perceived problem. Subsequent review of the identified concerns have indicated that most of these shift quality concerns that occurred once or twice early in the ownership experience were subsequently fixed by the normal automatic transmission adaptation process that occurs after the end-customer or owner receives the vehicle from the dealership. These particular shift quality concerns are attributable to a variation in shift quality that occurs because the controller for the automatic transmission has not yet learned how to compensate for manufacturing and part-to-part variation(s).
There is shown in FIG. 1 an exemplary illustration of various shift quality issues, such as shift shock due to tie-up and/or run-up and shift shock due to aggressive input speed gradient when a transmission controller has not learned to compensate for part-to-part and powertrain variation(s).
There also is described in Korean Publication No. 2007-0014566, a shift control system of an automatic transmission of a vehicle and a method thereof capable of adjusting control pressure by using under/over-shooting sense function. In such an invention and engine control sensing unit is provided or formed with various sensors. An engine control unit (ECU) controls the states of an engine by using the engine control sensing unit. A transmission control unit (TCU) performs a shift control process through a shift control driving unit by analyzing information of a shift sensing unit and information of the ECU through a predetermined algorithm. The TCU determines a synchronous point of a target shift gear by comparing a present input RPM of a turbine with a target RPM of the turbine. The TCU maintains a duty control in a present phase according to an under/over-shooting state of the synchronous point.
There also is described in Korean Publication No. 2008-0096902, a method for improving the shift feeling of an auto transmission. Such a method improves durability and shift feeling of the transmission by maintaining the control hydraulic pressure of a confliction element in minimum hydraulic pressure considering the low engine torque. More particularly, such a method includes the steps of: starting engine control of the speed-lowering of an engine torque at a shift starting point; reducing the engine torque from the shift starting point to target torque, enabling the shift by a release element and an engagement element in a state that the engine torque is maintained at the target torque for the interval of the inertial state, and getting the engine torque back to its initial torque after completion of the inertial state.
There also is described in Japanese Publication No. 11-094061 a shift controller of an automatic transmission. As further described, when a shift lever is operated from a D range to a second range after taking a pause in the third range, if the second gear speed is judged during the 4-3 shifting, in the 4-3 shift control, the shifting time is shortened by setting target engaging oil pressure (PTM) higher, whereby shifting response is improved and a shifting feeling is generated. In the 3-2 shifting, a target engaging oil pressure (PTB) is set similarly to a case of automatic shifting by a shifting map, and smooth shifting with little shift shock is performed.
While efforts have been undertaken to provide a controller that can learn and adapt operation of the transmission during day-to-day operation by the end customer, there still remains a need to reduce shift quality issues that are experienced early in the ownership experience.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
It thus would be desirable to provide new methods for a quick bedding-in of an automatic transmission of a new vehicle before ownership of the vehicle is transferred to the end customer. It would be particularly desirable to provide such a method that would minimize if not eliminate those shift quality issues generally attributable, for example, to powertrain or part-to-part variation(s) before transfer of ownership to the end customer. It also would be desirable to provide such methods that can be performed during end-of line testing of a vehicle without involving a significant impact on such end-of-line testing.